2D cameras for positioning and inspecting ultra-fine wires in semiconductor production

Wire bonding is a key process in semiconductor production. Extremely fine wires with diameters of 15 to 75 micrometres are used to create tiny electrical connections between a semiconductor chip and other components. The distances between the bond wires are often less than 100 micrometres. Any deviation, however small, can lead to connection errors. Wire bonding therefore requires the highest precision and forms the basis for the production of high-performance electronics, which are used in many different applications. 

F&S BONDTEC Semiconductor GmbH from Braunau, Austria, relies on image processing technology with industrial cameras from IDS Imaging Development Systems GmbH for the precise determination of wire positions and for quality assurance.

Wire bonders are available with various degrees of automation. With manual devices, each bond position must be approached manually before the corresponding connections can be made. Semi-automatic machines automatically position the wire after the first bond to create a wire bridge. 

Fully automatic machines use a structure recognition system to determine the position of the chips. Here, the production of all wire bridges is completely automatic. The operator only has to change the wire or tool on the bonder occasionally and take care of loading and unloading.

F&S Bondtec uses image processing with IDS industrial cameras for various tasks in the production process, especially in the semi-automatic machines of the 56i series and the automatic wire bonders of the 86 series. “Our wire bonds connect previously placed microchips or other components with different contact points on printed circuit boards and breathe life into the chips. 

“However, positional inaccuracies of the components can occur during the upstream processes. Our machines have to determine these positional inaccuracies using the IDS camera image and our own image recognition software and update the wire bond positions accordingly,” explains Johann Enthammer, Managing Director and CTO at F&S Bondtec.

For each bonding process, parameters such as ultrasonic amplitude, force, time or the movement sequence for setting up the bonding bridges must also be programmed in advance. The camera’s image feed is also used when creating these programmes. For example, you can drag a wire in the live image and change its position. The axes can also be adjusted by clicking on the image.

On the software side, the Austrian company relies on a specially developed image recognition library that works with position/pixel mapping, greyscale recognition and edge detection, for example.

Visual assessments of bond connections

Once the bonding process is complete, the camera is used again, as Johann Enthammer explains: “After welding, the wire bonds are visually checked by the operator via the camera image. Among other things, the position and shape of the bond bridges are assessed. The camera image therefore has more than just one function during the bonding process.”

Between one and seven industrial cameras are used per system. Depending on the type, these can be the particularly compact and cost-effective uEye XCP models. At just 29 x 29 x 17 millimetres, they are the smallest housed IDS cameras with C-mount and have a completely enclosed die-cast zinc housing. Their screw-type USB micro-B connection and compatibility with the Vision Standard (U3V/GenICam) simplify integration. F&S Bondtec also uses uEye CP cameras. These tiny powerhouses offer maximum functionality with extensive pixel pre-processing and are also perfect for multi-camera systems thanks to the internal 120 MB image memory for buffering image sequences. Users can choose from a large number of modern CMOS sensors. They also score points with a compact housing measuring just 29 x 29 x 29 millimetres.

Camera selection

The small design of the models and the large number of different sensors were important criteria when selecting the camera, as was the low thermal expansion. However, the free IDS peak software development kit with all the programming interfaces and software tools required for operating and programming the cameras was also crucial. Easy-to-understand convenience functions ensure an intuitive programming experience and quick and simple commissioning of the industrial cameras.

Johann Enthammer confirmed: “The driver shows very stable runtime behaviour. The easy-to-program API and the plug and play functions with running software convinced us. This is because there are many different use cases for our systems that can be implemented with the API without any problems. Our machines can be equipped with up to seven different bond heads. A different IDS camera can be integrated in each one.”

The wire bonders from F&S Bondtec ensure stable connections in semiconductor production. With the help of integrated image processing, the manufacturing quality and productivity of the systems can be further increased and rejects avoided. At the same time, the cameras make work easier for the operators. In addition to standard products, the company develops special machines and customised software solutions that also use AI models. “We definitely see a lot of potential for the use of artificial intelligence in our applications in the future,” says Johann Enthammer.